Costs of Reproduction in Breeding Female Mallards: Predation Risk during Incubation Drives Annual Mortality

Abstract

ABSTRACT. The effort expended on reproduction may entail future costs, such as reduced survival or fecundity, and these costs can have an important influence on life-history optimization. For birds with precocial offspring, hypothesized costs of reproduction have typically emphasized nutritional and energetic investments in egg formation and incubation. We measured seasonal survival of 3856 radio-marked female Mallards (Anas platyrhynchos) from arrival on the breeding grounds through brood-rearing or cessation of breeding. There was a 2.5-fold direct increase in mortality risk associated with incubating nests in terrestrial habitats, whereas during brood-rearing when breeding females occupy aquatic habitats, mortality risk reached seasonal lows. Mortality risk also varied with calendar date and was highest during periods when large numbers of Mallards were nesting, suggesting that prey-switching behaviors by common predators may exacerbate risks to adults in all breeding stages. Although prior investments in egg laying and incubation affected mortality risk, most relationships were not consistent with the cost of reproduction hypothesis; birds with extensive prior investments in egg production or incubation typically survived better, suggesting that variation in individual quality drove both relationships. We conclude that for breeding female Mallards, the primary cost of reproduction is a fixed cost associated with placing oneself at risk to predators while incubating nests in terrestrial habitats.RÉSUMÉ. L'effort investi à la reproduction peut avoir une incidence sur les coûts futurs -comme un faible taux de survie ou de fertilité -et ces coûts peuvent grandement influencer l'optimisation du cycle biologique. Chez les oiseaux dont les jeunes sont nidifuges, les coûts hypothétiques de la reproduction sont surtout liés aux efforts nutritionnel et énergétique investis dans la formation des oeufs et à l'incubation. Dans le cadre de cette étude, nous avons mesuré le taux de survie saisonnier de 3 856 Canards colverts (Anas platyrhynchos) femelles munies d'un émetteur radio, de leur arrivée sur les aires de nidification jusqu'à ce que l'élevage des jeunes soit complété ou jusqu'à l'échec de la nidification. Le taux de mortalité était de 2,5 fois plus élevé chez les femelles qui couvaient leurs oeufs en milieu terrestre, tandis qu'il a était à son plus bas niveau saisonnier au moment de l'élevage des jeunes en milieu aquatique. Le taux de mortalité a aussi varié en fonction de la date : il était à son maximum au moment où de nombreux Canards colverts nichaient, ce qui laisse croire que le changement de proies dans la diète des prédateurs communs pourrait exacerber le risque de mortalité chez les femelles à toutes les étapes de la nidification. Même si les efforts investis dans la ponte et l'incubation ont eu un effet sur le taux de mortalité, la plupart des relations n'étaient pas conformes aux prédictions de l'hypothèse des coûts de la reproduction; les femelles qui ont grandement investi dans la production d'oeufs ...

Breeding biology of the Spotted Barbtail (Premnoplex brunnescens)

“…Yet, even longer off-bouts up to 8 hrs have been observed in some tropical passerines in Asia that do not have bi-parental incubation (Martin et al 2013). The low attentiveness despite bi-parental incubation duties in Spotted Barbtails is surprising and may be favored by high adult survival to reduce daily energetic costs of incubation, allow more time to maintain individual physiological quality, and reduce predation risk of adults (Martin 2002, Martin and Schwabl 2008, Arnold et al 2012. Unfortunately, our capture and recapture rates of this species were too low for a reasonable estimate of survival, because we did not net in the steep creek valleys that they occupied.…”

Robust estimation of survival and contribution of captive‐bred Mallards Anas platyrhynchos to a wild population in a large‐scale release programme

“…Finally, our estimate did not include the breeding period, which is known to be associated with high mortality rates through predation of females on the nest (Arnold et al . ). For example, spring–summer survival rates of yearling wild Mallard females were 73% by Reynolds et al .…”

The effects of a large‐scale wind farm on breeding season survival of female mallards and blue‐winged teal in the Prairie Pothole Region

“…Several investigations have reported that survival of female ducks during the breeding season is lowest when females are nesting and are vulnerable to predators (Devries et al , Richkus et al , Arnold et al ). Consistent with these findings, survival of female mallards at TWF and REF was lowest when a high proportion of radio‐marked females were incubating nests (Fig.…”